<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>其他样式</title>
    <style>
        /*.hover {
            background-color: rgb(2, 2, 2);
            width: 1000px;
            font-size: 20px;
            cursor: text;
            color: #fff;
            line-height: 3em;
            visibility: hidden;
            opacity: 0.1;
    }
    */
        
        .main {
            height: 100px;
            background-color: teal;
            overflow: scroll;
        }
        
        .in {
            height: 140px;
            background-color: #ccc;
        }
    </style>
</head>

<body>
    <div class="main">
        <div class="in">123</div>
    </div>
</body>

</html>